Coadjustment of quercetin and hydrogen peroxide: the role of ROS in the cytotoxicity of quercetin.

Quercetin (QU) displays antioxidant and cell protective effects in most cell culture models, yet in some studies it is reported that QU shows prooxidant and cytotoxic effects. In order to explore the real role of ROS in QU's cytotoxicity, the cytotoxicity of QU and/or H2O2, as indicated by the proliferation and viability of HL-60 cells, was examined in this study. Both H2O2 and QU dose-dependently induced cell proliferation arrest and cell death. The cytotoxicity of QU could be diminished by the supplement of H2O2 in the culture medium, at the same time, the addition of QU also significantly attenuated H2O2- caused cytotoxicity. These results indicated that certain amounts of ROS are critical for the proliferation and viability of HL-60 cells, QU scavenged the necessary ROS, and hence led to the proliferation arrest and cell death; on the contrary, the excessive ROS, such as H2O2, are obviously harmful to HL-60 cells, under these conditions, QU protected cells through diminishing the excessive ROS in vivo. Thus QU exerted its effects on cells, including its cytotoxic and protective effects, mainly through its antioxidant activity. The malondialdehyde (MDA, an index of ROS level) assay further confirmed this conclusion, as the effects of QU, H2O2, or their combination on HL-60 cells were closely related with the variation of MDA amounts in vivo.

Allogeneic peripheral blood hematopoietic stem cell transplantation in malignant hematopoietic diseases.

To evaluate the use of allogeneic peripheral blood stem cell transplantation (allo-PBSCT) for treatment of acute and chronic leukemia, from March 1997 to January 2003, 21 adult patients with malignant hematopoietic diseases underwent allo-PBSCT from HLA-identical siblings (19 patients) and haplo-identical mother (one) and one B point site mismatched sibling (one). All donors were mobilized with G-CSF for 4 days and peripheral blood stem cells were collected by CS-3000 separator. The conditioning regimen included the high dose combination chemotherapy and TBI. Cyclosporine-A (CsA) plus a short course of MTX was used for GVHD prophylaxis in all patients. The results showed that after trans plantation, median time for the recovery of granuocyte > or = 0.5 x 10(9)/L and platelets > or = 20 x 10(9)/L were 12 (10 - 20) and 15 (11 - 35) days, respectively. Acute GVHD was observed in 8/17 patients (47%), of which one transplanted from HLA-haploidentical mother. Chronic GVHD occurred in 12/17 patients (70%). All of four female survivals did not show acute and chronic GVHD. Day 100 transplantation-related mortality was 14% (3/21). Relapse occurred in two patients (9.5%) who underwent allo-PBSCT in stage of non-remission at one and six months. After follow-up of 40 (15 - 70) months, 11 patients (52.4%) are still disease-free survival. These results suggested that peripheral blood stem cells produce a faster hematopoietic recovery and a lower relapse of leukemia. The rate of aGVHD is not increased when using the peripheral blood as source of stem cells; however, cGVHD continues to be a significant problem. Donors tolerated the procurement procedure without complications.

[Telomerase Activity Expressed in Acute Leukemia Cell]

To explore the possible linkage between telomerase and acute leukemia, we detected telomerase activity expressed in 3 leukemia cell lines, 22 acute leukemia bone marrow and 6 normal bone marrow with PCR ELISA assay. Results showed that telomerase activities of three leukemia cell lines were positive with the average (1.57 +/- 0.056) U, normal bone marrow samples average was (0.085 +/- 0.081) U, telomerase value from 22 acute leukemia patients was (0.512 +/- 0.294) U. Telomerase activity is higher expressed in acute leukemia than normal samples and decreased significantly after chemotherapy (P < 0.01). The results suggested that telomerase activity was related to some malignant diseases and might be used as a marker for tumor diagnosis and therapy.